David Cameron’s wife has given a revealing insight into their home life as she prepares to take a leading role in the General Election campaign.

In her first public interview, Samantha Cameron praised the Witney MP and Conservative Party leader’s strength, reliability and kindness.

But she said he was “definitely not perfect” and had “lots of very irritating habits”, such as being messy around the house.

The comments emerged after Mr Cameron disclosed that his wife was being deployed as a “secret weapon” to help him reach Downing Street.

Speaking at the couple’s London home to last night’s ITV1 programme Trevor McDonald Meets David Cameron, Mrs Cameron described how they met on a holiday 18 years ago.

She was a 21-year-old art student and a friend of his sister Clare, while he was 25 and a special adviser to Chancellor Norman Lamont at the Treasury.

“I was very young when we got engaged – I was only 23,” she said. “But I think I felt fairly confident that Dave was the one for me for lots of reasons.

“He’s a very strong kind of reliable person.”

Mrs Cameron, 38, the creative director of upmarket stationers Smythson, went on: “We’ve been together 18 years now and we’ve been through some fairly tough times, and I can honestly say that I don’t think in all that time he’s ever let me down.”

She said their children, Nancy and Arthur, helped Mr Cameron to switch off from politics.

“He’s a fantastic dad,” Mrs Cameron said. “They really make him laugh.

“They’ve got a fantastic sense of humour.

“And I think their weird and wonderful sort of take on life, he finds very relaxing. It’s a real kind of antidote to the kind of challenges in the office.”

But she added: “He’s definitely not perfect and like any husband he has lots of very irritating habits.

“I’d say one of the brilliant things about him is he loves cooking. But he makes a terrible mess. He’s not very good at clearing up as he goes along.”

Mrs Cameron added: “If he did become Prime Minister I would be incredibly proud of him.

“Our life would change, and that is daunting and I’m sure we would have to make sacrifices.

“But for me personally it would be a huge honour to do everything that I possibly could to support him and make sure that he could do the job to the very best of his abilities.”